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I have been using a boost framework from the link below for my iPhone Xcode project: https://goodliffe.blogspot.com/2010/09/building-boost-framework-for-ios-iphone.html

it works fine but I always get hundreds of Apple Mach-O Linker(id) Warnings like:

Direct access in __ZN5boost15program_options6detail7cmdline24handle_additional_parserERSt6vectorISsSaISsEE to global weak symbol __ZTVN5boost17bad_function_callE means the weak symbol cannot be overridden at runtime. This was likely caused by different translation units being compiled with different visibility settings.

How to get rid of those warnings in code?

edited: By set Symbols Hidden by Default = YES, I managed to get rid of most of the warnings but there are 3 more left which won't go away, can anyone tell me why?

edited again: After a rebuild the remaining 3 warning are gone as well! So my solution did work!

Cœur
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RoundPi
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6 Answers6

40

If boost is included by multiple projects, each project must have the same values for

 Symbols Hidden by Default
 Inline Methods Hidden
cyrilchampier
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  • Second time I arrived at this answer and it helped me fix the warning. No idea how the project could've ended up with "Inline methods hidden" being out of sync AGAIN. Xcode updates changed it? Ugh.. – Tomas Andrle Oct 23 '16 at 16:54
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    +1 Yep -- unlike the answer suggesting only `Symbols Hidden by Default` needed to match, I found that `Inline Methods Hidden` *also* needed to match. – aardvarkk Nov 03 '16 at 14:54
27

Doe just figured how to get rid of hundreds of warning like this : set for an entire target or project with the Symbols Hidden by Default build setting to YES

RoundPi
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7

The linker complains about different visibility settings between your project and Boost.

You can also fix that issue by recompiling Boost with the same compatibility settings.

Just add

cxxflags=-fvisibility=hidden

and 

cxxflags=-fvisibility-inlines-hidden

to the bjam command line.

Benoit Blanchon
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    -fvisibility=hidden implies -fvisibility-inlines-hidden. Only the former is necessary. – johnwbyrd Sep 19 '15 at 00:50
  • When I install boost I use `bootstrap.sh` and `./b2` as described in in the doc `getting_started/unix-variants.html` Where do a place these options? – wcochran Dec 14 '22 at 19:25
2

Setting Symbols Hidden by Default to NO and Inline Methods Hidden to NO worked for me.No need to add any flag to Other C++ flags

Desert Rose
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1

If boost is included by multiple projects, each project must have the same values for

Symbols Hidden by Default Inline Methods Hidden

nerith said is right, but in Xcode 4.6.3,they is not the above "Symbols Hidden by Default" and "Inline Methods Hidden", and i set the gcc_symbols_private_extern to yes, the warning is disappear.

Samuel Lu
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0

I also had this problem.

It turns out that I was carelessly doing something like this:

#pragma GCC visibility push(default)
#include <SomeExternalLibrary.h>
void myExampleSymbol();
#pragma GCC visibility pop

Which I solved by changing to:

#include <SomeExternalLibrary.h>
#pragma GCC visibility push(default)
void myExampleSymbol();
#pragma GCC visibility pop
OLL
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